It is widely known that easily accessible resources of fossil fuels are declining. In addition, the impact of the use of fossil fuels upon the environment has become increasingly apparent. As a result of this, it has become imperative that viable alternative energy sources are used as effectively and efficiently as possible. The use of turbines to capture the power of water flow, such as tidal, river and ocean current flows is becoming a viable source of alternative energy. The turbine equipment used to capture such water flow energy typically includes a shaft driven generator connected using a drivetrain to a rotor assembly. The rotor assembly includes a plurality of rotor blades that are driven by the water flow, so as to turn an input shaft of the drivetrain.
The turbine systems are typically deployed in multiple numbers at a particular location. Conventional systems comprise a hub which collects power from the multiple turbines and exports the power to shore via an export cable. Each turbine is arranged on a spur circuit from the hub. There might be multiple turbines on each spur circuit. The hub may be connected in a ring circuit with other hubs. The hub may export the power to shore at a higher voltage. It is estimated that the cables, which are necessarily located in regions of high tidal flow and/or large waves, have an estimated Mean Time Between Failure of approx. 5 years. The typical design lifetime of a turbine system is in the range of between 25 and 30 years. Therefore, it is likely that the cables will need to be replaced frequently during the lifetime of the hub and turbine. Dynamically positioned (DP) offshore construction vessels are typically required in order to replace damaged cables. The use of such vessels is however extremely expensive, so any system that reduces the time required to complete the replacement of damaged cables will significantly reduce costs and therefore improve the economic viability of the power generation system. Furthermore, if during replacement of a damaged cable, the other turbines are out of operation having further economic implications. In order to replace a damaged cable of one example of a conventional subsea power generation system with a hub, the whole hub complete with attached cables needs to be raised to the sea surface for intervention. This requires significantly more vessel time than the present invention, exposes the system to greater risk of further cable damage, requires large loops of excess cable to be arranged on the seabed and requires that all the power generation devices attached to the hub are inoperable for the duration of the operation. In order to replace cable(s) of another example of a conventional turbine system, the hub needs to be removed first. As the other turbines connected to the hub are unable to operate until the faulty cable and the hub have been replaced, the process of replacing the damaged cable loses more revenue for the operator than a single cable fault should warrant. Other known systems comprise a removable hub which does not need to be removed in order to replace faulty cables (as disclosed in GB2501249). However, this system does require the presence of twice the number of wetmate connectors compared to the present invention.